The basic object of the invention is to provide a rail vehicle having only a small unsprung mass, which is driven by a high-speed motor, particularly an electric motor. A more limited object consists in accommodating a high-ratio reuction gearing in a space-saving manner between the motor and the last gear member of the spring-mounted mass because accommodating the driving means in the space available for this purpose is frequently problematic, especially in high-speed rail vehicles. On the other hand, the reliable torque transmission from the spring-mounted to the unsprung part of the vehicle is of great importance, especially in high-speed rail vehicles.
The basic object of the invention is attained in that the electric motor acts through at least one gear set onto at least one hollow shaft which surrounds the drive axle and is connected to the same by means of an angularly and/or radially movable coupling, for example a universal joint coupling, the said gear set consisting of two reduction gearings which are connected in series and of which at least one is an angular drive, for example a bevel gear train.
Several advantageous embodiments are proposed to achieve the objects of the invention. Thus a tractive unit of the invention can be designed in such a manner that at least one spur gear system with a parallel drive and driven shaft is connected to the electric motor, the driven member of which is coupled with the driving member of the angular drive, for example the bevel gear train.
Advantageous installation conditions are obtained with a drive mechanism in which the spur gear system has coaxially arranged drive and driven members, the conditions being particularly favorable if the spur gear system is a planetary gearing with a fixed planet carrier because this enables a high reduction ratio to be obtained in a minimum of space.
The reduction ratio can be further increased while occupying approximately the same space by using a gearing in which the spur gear is a planetary gearing with a rotating planet carrier.
Various advantageous designs are possible for the angular drive. Thus the angular drive can advantageously be a bevel gear train having its gear axes in the same plane and comprising bevel gears which may be in the form of straight, skew or spiral bevel gears. For the design of the vehicle it may be expedient to use a transmission in which the angular drive is a bevel gear train with offset taxes (FIG. 5).
In the event that space conditions are problematic, it may be useful to employ a drive mechanism in which at least one angular drive, for example a bevel gear train, is connected to the electric motor, the driven member of such angular drive being coupled with the drive member of a spur gear system whose driven gear is arranged on or adjacent to the hollow shaft in a manner providing torque transmission thereto.
A further object of the invention consists in a development of the drive mechanism described above, to the effect that the spur gear system combines a high reduction ratio with a small center distance. This object is achieved by a drive mechanism in which a spur gear system having a substantially parallel drive and driven shaft is connected with the electric motor, such spur gear system substantially consisting of a drive pinion and an internally toothed spur gear which meshes with the said drive pinion, such internally toothed spur gear, which acts as a driven member, being coupled to the drive member of the angular drive, for example the bevel gear train, and the driven member of such angular drive, in turn, being coupled to the hollow shaft.
To permit a certain flexibility between the housing of the drive motor and the housing of the gearing without any detrimental effects on bearings and gears, a further embodiment of the invention provides for an angularly movable coupling, for example a toothed coupling, which is arranged between the drive motor and the drive pinion of the spur gear sytem.
To ensure a favorable position of the electric drive motor relative to the drive axle and to provide for low-noise operation, an expedient emobdiment consists in a drive mechanism in which the angular drive is a bevel gear train with offset axes.
Further advantages and characteristics of the invention are disclosed in the following description.